Deleted polls shouldn't be accessible through a public link

[SystemKeeper]

What is going wrong?

Describe the bug
Not sure if this is intended behaviour or not. When a poll is deleted, it is moved to "Deleted polls", which is fine. Personally I would've expected that public links will be kept (in case a poll is restored afterwards), but wouldn't be accessible through this public link.

To Reproduce
Steps to reproduce the behavior:

1. Create a poll
2. Create a public link
3. Delete the poll
4. Try to access the poll with the created public link.

Expected behavior
As the link is a public link, I would've expected to get an error (same as you were trying to access a non-existant public link), but instead the poll is still shown.
Also: I can still enter a Name and create a new personal link! I cant vote for anything but I could add public links.

Screenshots
If applicable, add screenshots to help explain your problem.

Information about your polls installation

Polls version? 1.1.5

Fresh installation or update from a prior version (from which one)?

Update

How did you install this version?(Appstore or describe installation)
Manual

Information about your Instance of Nextcloud/ownCloud

Nextcloud or ownCloud? NC

Which Version? 17.02